It sounds good overall, but I would change "you have all", to "you all
have".
The sencetnce after that one is a bit long, you might waht to break it
up into two sentences. The last part of that sentence should be it's
own, and you might want to say, "By sticking together I know that we
can get through this." The other way makes it sound as if he is not
too sure they will.
The part where they put their hands on top of eachother could be a bit
different. If I already know these charachters from before in the
story and know that they are all there you could just say, "Mac was
the fist to put his hand on top of theirs as the rest followed.
Smiling at eachother the group shouted, 'Together!' "
It does not have to exactly be like that but something along those
lines would be my suggestion. Good Luck!!!